:root{--bg:#fafaf7;--card:#fff;--ink:#1c1b19;--mute:#6f6c66;--line:#e6e3dc;--accent:#2f6fed;--accent-soft:#e3ecff;--hot:#ffe9a8;--hot-ink:#5a4200;--ok:#1f9d63;--code-bg:#f4f2ec;--shadow:0 1px 2px rgba(0,0,0,.05)}
@media (prefers-color-scheme:dark){:root:not([data-theme=light]){--bg:#15161a;--card:#1d1f25;--ink:#ecebe6;--mute:#9a978f;--line:#2c2f37;--accent:#6b9bff;--accent-soft:#1f2c4d;--hot:#5a4a12;--hot-ink:#ffe9a8;--ok:#43c88a;--code-bg:#181a1f;--shadow:none}}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.5 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif}
a{color:var(--accent);text-decoration:none}
.wrap{max-width:920px;margin:0 auto;padding:20px 16px 110px}
h1{font-size:28px;margin:6px 0 4px;letter-spacing:-.02em}
.sub{color:var(--mute);margin:0 0 24px}
.tag{display:inline-block;font-size:12px;padding:2px 9px;border-radius:99px;background:var(--accent-soft);color:var(--accent);font-weight:600;margin-right:6px}
.tag.Easy{background:#dcf5e8;color:#157a4b}.tag.Medium{background:#fff0cf;color:#8a5a00}
@media (prefers-color-scheme:dark){.tag.Easy{background:#16382a;color:#6be0a4}.tag.Medium{background:#3d3010;color:#ffd26a}}
/* index grid */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:14px}
.card{display:block;background:var(--card);border:1px solid var(--line);border-radius:14px;padding:16px;color:var(--ink);box-shadow:var(--shadow);transition:transform .15s,border-color .15s}
.card:hover{transform:translateY(-2px);border-color:var(--accent)}
.card .num{font-size:13px;color:var(--mute);font-weight:600}.card h3{margin:4px 0 10px;font-size:17px}
.card .mini{display:flex;gap:3px;margin-top:12px}.card .mini i{width:22px;height:22px;border-radius:5px;background:var(--code-bg);border:1px solid var(--line)}.card .mini i.h{background:var(--hot);border-color:transparent}
/* problem sections */
.sec{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:16px 18px;margin:0 0 14px;box-shadow:var(--shadow)}
.sec>h2{display:flex;align-items:center;gap:10px;font-size:13px;text-transform:uppercase;letter-spacing:.08em;color:var(--mute);margin:0 0 12px}
.sec>h2 b{display:inline-grid;place-items:center;width:22px;height:22px;border-radius:50%;background:var(--accent);color:#fff;font-size:12px}
.q{font-size:18px;margin:0 0 12px}
.io{display:grid;grid-template-columns:1fr auto 1fr;gap:10px;align-items:center}
.io div{background:var(--code-bg);border-radius:10px;padding:10px 12px;font:14px ui-monospace,Menlo,monospace;overflow-x:auto}
.io small{display:block;font:11px -apple-system,sans-serif;color:var(--mute);text-transform:uppercase;letter-spacing:.06em;margin-bottom:2px}
.io .arrow{background:none;padding:0;font-size:22px;color:var(--mute)}
.tabs{display:flex;gap:6px;margin:0 0 10px;flex-wrap:wrap}
.tabs button{border:1px solid var(--line);background:var(--card);color:var(--ink);padding:5px 12px;border-radius:99px;cursor:pointer;font-size:13px}
.tabs button.on{background:var(--accent);color:#fff;border-color:var(--accent)}
pre.code{margin:0;background:var(--code-bg);border-radius:10px;padding:8px 0;overflow-x:auto;font:13.5px/1.55 ui-monospace,Menlo,Consolas,monospace}
pre.code .ln{display:block;padding:0 14px 0 8px;border-left:3px solid transparent;white-space:pre;transition:background .2s}
pre.code .ln i{display:inline-block;width:26px;color:var(--mute);font-style:normal;user-select:none;opacity:.6}
pre.code .ln.on{background:var(--hot);border-left-color:#e5a400;color:var(--hot-ink)}
.k{color:#a626a4}.s{color:#2c8a3a}.c{color:var(--mute);font-style:italic}.n{color:#b76b00}
@media (prefers-color-scheme:dark){.k{color:#d98cff}.s{color:#7fd88a}.n{color:#ffb454}}
.meta{display:flex;gap:14px;margin-top:10px;font-size:13px;color:var(--mute);flex-wrap:wrap}.meta b{color:var(--ink)}
/* flow */
.flow{display:flex;flex-wrap:wrap;gap:6px 0;align-items:center}
.flow .st{padding:7px 12px;border-radius:99px;border:1px solid var(--line);font-size:13px;color:var(--mute);cursor:pointer;background:var(--card);transition:all .2s}
.flow .st.done{color:var(--ink);border-color:var(--ok)}
.flow .st.on{background:var(--accent);color:#fff;border-color:var(--accent);transform:scale(1.06);font-weight:600}
.flow .ar{color:var(--mute);margin:0 4px;font-size:13px}
/* stage */
.stage{min-height:150px;display:flex;flex-direction:column;gap:14px;justify-content:center}
.row{display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.row .nm{width:92px;flex:none;font:12px ui-monospace,Menlo,monospace;color:var(--mute);text-align:right}
.cells{display:flex;gap:5px;flex-wrap:wrap}
.cell{min-width:40px;height:40px;padding:0 6px;display:grid;place-items:center;border-radius:9px;border:1.5px solid var(--line);background:var(--code-bg);font:600 16px ui-monospace,Menlo,monospace;transition:background .3s,border-color .3s,transform .3s}
.cell.sp{color:var(--mute);font-weight:400}
.cell.hot{background:var(--hot);border-color:#e5a400;color:var(--hot-ink);transform:translateY(-4px)}
.cell.pop{animation:pop .5s}
@keyframes pop{0%{transform:scale(.7)}60%{transform:scale(1.15)}100%{transform:scale(1)}}
.facts{display:flex;gap:8px;flex-wrap:wrap}.facts span{background:var(--accent-soft);color:var(--accent);border-radius:8px;padding:3px 10px;font:600 13px ui-monospace,Menlo,monospace}
.cap{margin:14px 0 0;font-size:15px;min-height:24px}
.recap{border-left:3px solid var(--ok);padding:2px 12px;margin:10px 0 0;font-size:14px}
details{margin-top:6px;font-size:14px;color:var(--mute)}details summary{cursor:pointer;color:var(--ink);font-weight:600}details li{margin:4px 0}
/* controls */
.bar{position:fixed;left:0;right:0;bottom:0;background:color-mix(in srgb,var(--card) 92%,transparent);backdrop-filter:blur(8px);border-top:1px solid var(--line);padding:10px 16px;z-index:9}
.bar .in{max-width:920px;margin:0 auto;display:flex;align-items:center;gap:10px}
.bar button{border:1px solid var(--line);background:var(--card);color:var(--ink);height:40px;padding:0 16px;border-radius:10px;cursor:pointer;font-size:15px;font-weight:600}
.bar button:hover{border-color:var(--accent)}.bar button:disabled{opacity:.35;cursor:default}
.bar button.play{background:var(--accent);color:#fff;border-color:var(--accent);min-width:104px}
.bar .prog{flex:1;height:6px;border-radius:9px;background:var(--line);overflow:hidden}.bar .prog i{display:block;height:100%;width:0;background:var(--accent);transition:width .3s}
.bar .ct{font-size:13px;color:var(--mute);min-width:44px;text-align:right}
.bar select{height:40px;border-radius:10px;border:1px solid var(--line);background:var(--card);color:var(--ink);padding:0 6px}
@media (max-width:560px){.io{grid-template-columns:1fr}.io .arrow{transform:rotate(90deg);text-align:center}.row .nm{width:100%;text-align:left}.bar .prog,.bar select{display:none}.bar .in{justify-content:center}}

/* layout: wide = code left, flow+diagram right; narrow = diagram docked above the controls */
.work{display:block}
@media (min-width:1000px){.wrap{max-width:1180px}.work{display:grid;grid-template-columns:1fr 1fr;gap:14px;align-items:start}.work .sec{margin:0 0 14px}.codeSec,.right{position:sticky;top:12px}}
@media (max-width:999px){.dock{position:sticky;bottom:62px;z-index:5;box-shadow:0 -6px 18px rgba(0,0,0,.12);padding:10px 14px;margin-bottom:14px}.dock .stage{min-height:0;gap:8px}.dock .cell{min-width:34px;height:34px;font-size:14px}.dock .cap{margin-top:8px;font-size:14px}.wrap{padding-bottom:300px}}
.pnav{display:flex;justify-content:space-between;align-items:center;gap:10px;margin:0 0 6px}.pnav a{font-weight:600}.pnav .go,.pnav.bot a{background:var(--card);border:1px solid var(--line);padding:6px 14px;border-radius:99px}.pnav .pos{color:var(--mute);font-size:13px}.pnav.bot{margin-top:14px}
.cw{display:inline-flex;flex-direction:column;align-items:center;gap:2px}.mk{height:16px;font:700 12px ui-monospace,Menlo,monospace;color:var(--accent)}.cell.nul{border-style:dashed;background:none;opacity:.5}.lk{color:var(--mute);align-self:flex-start;line-height:40px;margin:0 -1px}.grid2{display:flex;flex-direction:column;gap:2px}.grid2 .cells{gap:5px}.grid2 .mk{display:none}.sec h2 .cnt{margin-left:auto;font-size:12px}
.grp{font-size:15px;margin:28px 0 10px;color:var(--mute);text-transform:uppercase;letter-spacing:.07em}.grp span{background:var(--accent-soft);color:var(--accent);border-radius:99px;padding:1px 8px;font-size:12px;margin-left:6px}.card h3{margin-bottom:8px}
.ptop{margin:0 0 6px}.pbar{height:8px;border-radius:9px;background:var(--line);overflow:hidden}.pbar i{display:block;height:100%;background:var(--ok);transition:width .4s}
.prow{display:flex;align-items:center;gap:14px;flex-wrap:wrap;margin-top:8px;font-size:14px}.prow .cont{font-weight:600}.prow button{margin-left:auto;border:1px solid var(--line);background:var(--card);color:var(--mute);border-radius:8px;padding:3px 10px;cursor:pointer}
.card{position:relative}.card.done{border-color:var(--ok)}.card.done::after{content:"✓";position:absolute;top:12px;right:14px;width:22px;height:22px;border-radius:50%;background:var(--ok);color:#fff;display:grid;place-items:center;font-size:13px;font-weight:700}
.grp .pc{background:var(--line);color:var(--mute);border-radius:99px;padding:1px 8px;font-size:12px;margin-left:6px}.grp .pc.all{background:var(--ok);color:#fff}
.bar button.dn.on{background:var(--ok);border-color:var(--ok);color:#fff}
.q{font-size:19px;line-height:1.45}.why,.idea{margin:12px 0 0;padding:10px 14px;border-radius:10px;font-size:15px;line-height:1.5}.why{background:var(--code-bg)}.idea{background:var(--accent-soft);color:var(--ink)}.why b,.idea b{display:block;font-size:12px;text-transform:uppercase;letter-spacing:.06em;color:var(--mute);margin-bottom:2px}.idea b{color:var(--accent)}
/* landing page index */
.tools{display:flex;gap:8px;margin:0 0 12px}.tools button{border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:10px;padding:6px 14px;cursor:pointer;font-size:14px;font-weight:600}.tools button:hover{border-color:var(--accent)}
.thead,.r{display:grid;grid-template-columns:28px 40px 62px 1fr 74px 30px;gap:8px;align-items:center}
.thead{padding:0 12px;font-size:11px;text-transform:uppercase;letter-spacing:.07em;color:var(--mute);margin-bottom:6px}
.topic{background:var(--card);border:1px solid var(--line);border-radius:14px;margin:0 0 12px;overflow:hidden;box-shadow:var(--shadow)}
.th{width:100%;display:flex;align-items:center;gap:10px;padding:12px 14px;border:0;background:var(--code-bg);color:var(--ink);font:700 15px -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;cursor:pointer;text-align:left}
.th .chev{width:14px;color:var(--mute)}.th .pc{margin-left:auto;background:var(--line);color:var(--mute);border-radius:99px;padding:1px 9px;font-size:12px}.th .pc.all{background:var(--ok);color:#fff}
.tb{display:none}.topic.open .tb{display:block}
.rowx{border-top:1px solid var(--line)}.rowx .r{padding:9px 12px}
.rowx .sl,.rowx .lc{color:var(--mute);font:13px ui-monospace,Menlo,monospace}.rowx .ti{font-weight:600;color:var(--ink)}.rowx .ti:hover{color:var(--accent)}
.qt{width:26px;height:26px;border:1px solid var(--line);background:var(--card);color:var(--mute);border-radius:7px;cursor:pointer;font-size:12px}.qt:hover{border-color:var(--accent);color:var(--accent)}
.ck{width:22px;height:22px;border-radius:6px;border:2px solid var(--mute);background:var(--card);color:#fff;display:grid;place-items:center;font-size:14px;font-weight:700;cursor:pointer;padding:0}.ck:hover{border-color:var(--ok)}.rowx.done .ck.rd,.ck.wk[aria-checked="true"]{background:var(--ok);border-color:var(--ok)}.rowx.done .ck.rd::after,.ck.wk[aria-checked="true"]::after{content:"✓"}.thead .dh{text-align:center;font-size:10px}.rowx.done .ti{color:var(--mute)}
.qa{display:none;padding:2px 14px 14px 46px}.rowx.qopen .qa{display:block}.qa .q{font-size:16px;margin:0 0 10px}.qa .open{display:inline-block;margin-top:12px;font-weight:600}
.thead .ti{grid-column:4}
@media (max-width:560px){.thead,.r{grid-template-columns:26px 30px 1fr 30px 30px;gap:6px}.thead .lc,.rowx .lc,.thead span:nth-child(5),.rowx .tag{display:none}.thead span:nth-child(5){display:none}.qa{padding-left:14px}}
.ck{width:26px;height:26px;border:2px solid var(--ink);border-radius:7px;opacity:.8}.ck:hover{opacity:1;border-color:var(--ok)}.rowx.done .ck.rd,.ck.wk[aria-checked="true"]{opacity:1}.thead,.r{grid-template-columns:28px 40px 62px 1fr 74px 48px 48px}h1{margin-bottom:14px}
.plist{margin:0 0 18px}.ph{width:100%;display:flex;align-items:center;gap:10px;padding:14px 16px;border:1px solid var(--line);border-radius:14px;background:var(--card);color:var(--ink);font:800 20px -apple-system,BlinkMacSystemFont,sans-serif;letter-spacing:-.01em;cursor:pointer;text-align:left;box-shadow:var(--shadow)}.ph:hover{border-color:var(--accent)}.ph .chev{width:16px;color:var(--mute);font-size:16px}.pb{display:none;margin-top:12px}.plist.open .pb{display:block}
.tools .gap{flex:1}.tools .flt[aria-pressed=true]{background:var(--accent);border-color:var(--accent);color:#fff}
.rowx.hl{background:var(--accent-soft);box-shadow:inset 3px 0 0 var(--accent)}.ph small{font-size:13px;font-weight:500;color:var(--mute);margin-left:6px}
.sec>h2 .arrows{margin-left:auto;display:flex;align-items:center;gap:6px;text-transform:none;letter-spacing:0}.arrows button{width:32px;height:28px;border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:8px;cursor:pointer;font-size:13px;padding:0}.arrows button:hover:not(:disabled){border-color:var(--accent);color:var(--accent)}.arrows button:disabled{opacity:.3;cursor:default}.arrows .dct{font:12px ui-monospace,Menlo,monospace;color:var(--mute);min-width:44px;text-align:center}

/* diagram transitions */
.cells{position:relative}.cw{display:inline-flex}.cw.new .cell{animation:cellin .35s ease}.row.rnew{animation:rowin .35s ease}
@keyframes cellin{from{opacity:0;transform:translateY(8px) scale(.85)}to{opacity:1;transform:none}}
@keyframes rowin{from{opacity:0;transform:translateY(-6px)}to{opacity:1;transform:none}}
.cell{transition:background .35s,border-color .35s,color .35s,transform .35s,opacity .35s}
.cell.pop{animation:pop .5s}
.ptr{position:absolute;transform:translateX(-50%);font:700 12px ui-monospace,Menlo,monospace;color:var(--accent);opacity:0;transition:left .45s cubic-bezier(.4,0,.2,1),top .45s cubic-bezier(.4,0,.2,1),opacity .3s;white-space:nowrap;pointer-events:none}
.ptr.on{opacity:1}.ptr::before{content:"▲";display:block;font-size:8px;line-height:8px;text-align:center}
.listrow .cw:not(:last-child)::after{content:"→";color:var(--mute);line-height:40px;margin:0 2px 0 5px}.listrow{gap:0}
.fc{background:var(--accent-soft);color:var(--accent);border-radius:8px;padding:3px 10px;font:600 13px ui-monospace,Menlo,monospace;animation:cellin .3s ease}
.cap.swap{animation:capin .3s ease}@keyframes capin{from{opacity:0;transform:translateY(4px)}to{opacity:1;transform:none}}
.cw{flex-direction:row;align-items:flex-start;gap:0}
.modes{display:flex;margin-left:auto;border:1px solid var(--line);border-radius:99px;overflow:hidden;text-transform:none;letter-spacing:0}.modes button{border:0;background:var(--card);color:var(--mute);padding:3px 11px;font-size:12px;font-weight:600;cursor:pointer}.modes button.on{background:var(--accent);color:#fff}.modes+.arrows{margin-left:10px}
.vt{background:var(--code-bg);border:1px solid var(--line);border-radius:99px;padding:1px 9px;font-size:12px;font-weight:700;color:var(--mute)}.vt.best{background:var(--accent-soft);border-color:transparent;color:var(--accent)}.modes button:disabled{opacity:.4;cursor:default}
.copyw{margin-left:auto;text-transform:none;letter-spacing:0}.copyw button{border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:8px;padding:3px 12px;font-size:12px;font-weight:600;cursor:pointer}.copyw button:hover{border-color:var(--accent);color:var(--accent)}.copyw button.ok{background:var(--ok);border-color:var(--ok);color:#fff}

/* answer at a glance */
.sum>h2{font-size:15px;color:var(--ink);text-transform:none;letter-spacing:0}
.sumgrid{display:grid;grid-template-columns:minmax(0,5fr) minmax(0,7fr);gap:12px;align-items:start}
@media (max-width:999px){.sumgrid{grid-template-columns:1fr}}
.sleft{display:flex;flex-direction:column;gap:12px}
.pn{border-radius:12px;padding:14px 16px;border:1px solid var(--line)}.pn h3{margin:0 0 6px;font-size:18px}.pn h3 small{font-size:12px;font-weight:500;color:var(--mute)}.pn p{margin:6px 0}.pn ul{margin:6px 0;padding-left:20px}.pn li{margin:4px 0}
.pq{background:color-mix(in srgb,#4a90e2 14%,var(--card))}.pc{background:var(--code-bg);padding:6px 0}.pk{background:color-mix(in srgb,#f0b429 16%,var(--card))}.px{background:color-mix(in srgb,#9b6bdc 14%,var(--card))}.pw{background:color-mix(in srgb,#43b36a 13%,var(--card))}
.scode{background:none;margin:0}.spio{font-size:14px}.spio b{color:var(--mute);font-size:11px;text-transform:uppercase;letter-spacing:.06em;margin-right:6px}
.sf{display:inline-block;background:color-mix(in srgb,#e04a4a 16%,var(--card));color:var(--ink);border-radius:6px;padding:0 7px;font:600 12px ui-monospace,Menlo,monospace;margin:2px 4px 2px 0}.sf.b{background:color-mix(in srgb,#4a90e2 20%,var(--card))}
.sstep{display:grid;grid-template-columns:minmax(120px,2fr) minmax(0,4fr) minmax(110px,2fr);gap:10px;align-items:center;padding:10px 8px;border-top:1px solid color-mix(in srgb,var(--ink) 10%,transparent)}
.sinfo b{font-size:14px}.sfacts{margin-top:4px}.snote{font-size:13px;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:8px 10px}
.sgap{text-align:center;color:var(--mute);font-size:12px;padding:6px 0}
.sres{background:color-mix(in srgb,#43b36a 10%,transparent);border-radius:10px}
.srow{display:flex;align-items:flex-start;gap:8px;margin:4px 0;flex-wrap:wrap}.snm{width:64px;flex:none;font:11px ui-monospace,Menlo,monospace;color:var(--mute);text-align:right;line-height:34px}
.scells{display:flex;gap:4px;flex-wrap:wrap}.sgrid{display:flex;flex-direction:column;gap:3px}.sc{display:inline-flex;flex-direction:column;align-items:center}
.sc .cell{min-width:34px;height:34px;font-size:14px;animation:none!important;transform:none!important}.smk{height:14px;font:700 11px ui-monospace,Menlo,monospace;color:var(--accent)}.sgrid .smk{display:none}
.slist .sc:not(:last-child)::after{content:"→";position:absolute;color:var(--mute)}
@media (max-width:760px){.sstep{grid-template-columns:1fr}}
.exs{display:flex;margin-left:8px;border:1px solid var(--line);border-radius:99px;overflow:hidden;text-transform:none;letter-spacing:0}.exs button{border:0;background:var(--card);color:var(--mute);padding:3px 11px;font-size:12px;font-weight:600;cursor:pointer}.exs button.on{background:#c0392b;color:#fff}.why.edge{background:color-mix(in srgb,#e74c3c 10%,var(--card));border-left:3px solid #c0392b}.why.edge code{font:13px ui-monospace,Menlo,monospace;background:var(--card);border-radius:5px;padding:1px 6px}.pe{background:color-mix(in srgb,#e74c3c 12%,var(--card))}.modes+.exs+.arrows{margin-left:10px}
.tools .sync[data-st=ok]{border-color:var(--ok,#2e9e5b)}.tools .sync[data-st=err]{border-color:#d33;color:#d33}.tools{flex-wrap:wrap}

@media (max-width:560px){.thead,.r{grid-template-columns:26px 30px 1fr 30px 30px;gap:6px}}
@media (max-width:560px){
.wrap{padding-left:12px;padding-right:12px}
h1{font-size:28px}
.thead .ti{grid-column:auto}
.thead span:nth-child(3){display:none}
.tools{display:grid;grid-auto-flow:column;grid-template-rows:repeat(3,40px);grid-auto-columns:max-content;overflow-x:auto;-webkit-overflow-scrolling:touch;scrollbar-width:none;margin:0 -12px 12px;padding:0 12px 4px;gap:8px}
.tools::-webkit-scrollbar{display:none}
.tools button,.tools .gap{flex:0 0 auto;white-space:nowrap}
.tools .gap{display:none}
.tools button{min-height:40px}
.thead .dh{font-size:9px;letter-spacing:0}
.ck{width:30px;height:30px}
.thead,.r{grid-template-columns:34px 26px 1fr 34px 34px;gap:6px}
.rowx .r{padding:6px 10px;min-height:48px}
.qt{width:32px;height:32px}
.th{padding:14px}
.rowx .ti{font-size:15px;line-height:1.3}
}
@media (max-width:999px){.sumgrid{grid-template-columns:minmax(0,1fr)}.sleft,.sumgrid>*{min-width:0}}
@media (max-width:560px){
.sec{padding:14px}
.bar{padding:8px 10px}
.bar .in{gap:6px}
.bar button{padding:0 10px;height:44px;font-size:14px}
.bar button.play{min-width:0}
}
@media (max-width:560px){
.dock h2{flex-wrap:wrap;row-gap:8px}
.dock h2 .modes,.dock h2 .exs{order:3;flex:1 1 100%;display:flex;gap:6px}
.dock h2 .modes button,.dock h2 .exs button{flex:1;white-space:nowrap}
.dock h2 .arrows{margin-left:auto}
}

/* Understanding the code */
.und{margin-top:14px}.und h2{margin:0 0 10px}.ub{margin-bottom:10px}.ub h3 b{display:inline-grid;place-items:center;width:24px;height:24px;margin-right:8px;border-radius:50%;background:var(--line);font-size:13px}
.ub code,.utake code{font-family:ui-monospace,Menlo,monospace;font-size:.92em;padding:1px 5px;border-radius:5px;background:var(--line)}
.utw{overflow-x:auto;margin:8px 0}.ut{border-collapse:collapse;width:100%;font-size:14px}.ut th,.ut td{text-align:left;padding:7px 10px;border:1px solid var(--line);vertical-align:top}.ut th{background:var(--line)}
.ucode{margin:8px 0;padding:10px 12px;overflow-x:auto}.utake{border-left:4px solid var(--line)}

/* Section header counts + filter highlight */
.bd{margin-left:auto;display:flex;flex-wrap:wrap;gap:5px;justify-content:flex-end;font:600 12px -apple-system,BlinkMacSystemFont,sans-serif;letter-spacing:0}
.bp{padding:1px 9px;border-radius:99px;background:var(--line);color:var(--mute);white-space:nowrap}.bp.rd{color:var(--ok)}.bp.hi{background:var(--accent);color:#fff}
.plist:not(.open)>.ph .bp.tot,.topic:not(.open)>.th .bp.tot{color:var(--ink)}
.plist.hl>.ph,.topic.hl>.th{background:var(--accent-soft);box-shadow:inset 4px 0 0 var(--accent)}
.plist:not(.open)>.ph .bp.rd,.plist:not(.open)>.ph .bp.wr,.topic:not(.open)>.th .bp.rd,.topic:not(.open)>.th .bp.wr{}
@media (max-width:560px){.ph .bd,.th .bd{font-size:11px}.bp{padding:1px 7px}}

/* Pattern note per topic */
.about{margin:8px 10px;border:1px solid var(--line);border-radius:10px;background:var(--card)}.about>summary{cursor:pointer;padding:9px 12px;font-weight:700;font-size:14px}.about>summary small{font-weight:500;color:var(--mute);margin-left:6px}
.about p,.about ol,.about pre{margin:6px 12px}.about ol{padding-left:22px}.about li{margin:3px 0}.about pre{font-size:13px;line-height:1.45}
@media (max-width:560px){.about>summary small{display:block;margin:2px 0 0}.about{margin:8px 6px}}

.sdnav{margin:8px 0}.sdnav a{display:inline-block;padding:8px 14px;border-radius:10px;border:1px solid var(--line);background:var(--card);color:var(--accent);font-weight:700;text-decoration:none}.sdnav small{font-weight:500;color:var(--mute)}

/* Animated pattern demo */
.tv{margin:6px 12px 10px;padding:10px 12px;border:1px solid var(--line);border-radius:10px;background:var(--code-bg);overflow-x:auto}
.vsvg{display:block;width:100%;max-width:420px;margin:0 auto 6px}.ve{stroke:var(--mute);stroke-width:1.5}.ve.off{opacity:.18}
.vg circle{fill:var(--card);stroke:var(--mute);stroke-width:1.5;transition:fill .35s,stroke .35s}.vg text{font:700 12px -apple-system,BlinkMacSystemFont,sans-serif;fill:var(--ink)}
.vg.off{opacity:.2}.vg.queued circle{stroke:var(--accent);stroke-dasharray:4 3}.vg.seen circle{fill:var(--accent-soft);stroke:var(--accent)}.vg.cur circle{fill:var(--hot);stroke:var(--accent);stroke-width:2.5}.vg.cur text{fill:var(--hot-ink)}
.vrow{display:flex;align-items:flex-start;gap:8px;margin:4px 0}.vn{flex:0 0 118px;font-size:12px;color:var(--mute);padding-top:6px}.vcells{display:flex;flex-wrap:wrap;gap:4px}.vcol{display:flex;flex-direction:column;align-items:center}
.vc{min-width:32px;padding:4px 7px;border:1.5px solid var(--mute);border-radius:7px;background:var(--card);font:600 13px ui-monospace,Menlo,monospace;text-align:center;transition:background .3s,border-color .3s,opacity .3s}
.vc.hot{background:var(--hot);color:var(--hot-ink);border-color:var(--accent)}.vc.ok{background:var(--accent-soft);border-color:var(--accent)}.vc.bad{opacity:.35;text-decoration:line-through}.vp{min-height:15px;font:700 11px -apple-system,sans-serif;color:var(--accent)}
.vnote{margin:8px 0 4px;font-size:14px;min-height:40px}.vbar{display:flex;align-items:center;gap:10px}.vbtn{border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:8px;padding:2px 10px;cursor:pointer}.vct{font-size:12px;color:var(--mute)}
@media (max-width:560px){.vrow{flex-direction:column;gap:2px}.vn{flex:none;padding-top:0}.vc{min-width:28px;padding:3px 5px;font-size:12px}}

/* Notepad popup */
.padfab{position:fixed;right:14px;top:42%;z-index:20;width:46px;height:46px;border-radius:50%;border:1px solid var(--line);background:var(--card);color:var(--ink);box-shadow:0 2px 10px rgba(0,0,0,.18);cursor:pointer;display:grid;place-items:center}.padfab:hover{border-color:var(--accent);color:var(--accent)}.padfab.has::after{content:"";position:absolute;top:7px;right:7px;width:9px;height:9px;border-radius:50%;background:var(--ok)}
.padov{position:fixed;inset:0;z-index:40;background:rgba(0,0,0,.45);display:flex;align-items:center;justify-content:center;padding:12px}.padov[hidden]{display:none}
.padbox{width:min(780px,100%);height:min(78vh,720px);background:#fff;color:#111;border-radius:14px;box-shadow:0 12px 40px rgba(0,0,0,.35);display:flex;flex-direction:column;overflow:hidden}
.padhd{display:flex;align-items:center;gap:10px;padding:10px 14px;border-bottom:1px solid #e5e5e5;font:14px -apple-system,BlinkMacSystemFont,sans-serif}.padsub{color:#777;flex:1;min-width:0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.padbt{display:flex;gap:6px}
.padbt button{border:1px solid #ccc;background:#fff;color:#111;border-radius:8px;padding:5px 11px;font:600 13px -apple-system,sans-serif;cursor:pointer}.padbt button:hover{background:#f3f3f3}
.padta{flex:1;width:100%;border:0;outline:0;resize:none;padding:14px 16px;background:#fff;color:#111;font:14px/1.55 ui-monospace,Menlo,Consolas,monospace;tab-size:4}
@media (max-width:560px){.padfab{right:8px;top:auto;bottom:74px;width:42px;height:42px}.padbox{height:84vh}}

.lcl{margin:6px 0 0;font-size:13px}.lcl a{color:var(--accent);text-decoration:none}.lcl a:hover{text-decoration:underline}

.stmt p{margin:8px 0;line-height:1.55}.stmt code{font-family:ui-monospace,Menlo,monospace;font-size:.92em;padding:1px 5px;border-radius:5px;background:var(--line)}.sth{margin:14px 0 4px;font-size:15px}.stc{margin:6px 0;padding:10px 12px;overflow-x:auto}.stmt ul{margin:6px 0;padding-left:22px}.stmt li{margin:4px 0}

.qfull{margin:6px 0;border:1px solid var(--line);border-radius:10px;padding:0 14px;background:var(--card,transparent)}.qfull>summary{cursor:pointer;padding:10px 0;font-weight:600;font-size:14px}.qfull[open]>summary{border-bottom:1px solid var(--line);margin-bottom:6px}

.rowx.lt .ti::after{content:" ⏰";font-size:.85em}.dn.lt.on{background:var(--accent);color:#fff}.flt[data-flt="later"]{border-style:dashed}

.treebox{overflow-x:auto;padding:4px 0}.tsvg{display:block;margin:0 auto;max-width:100%;height:auto}.tsvg line{stroke:var(--mute);stroke-width:1.6;opacity:.55}
.tn circle{fill:var(--card);stroke:var(--accent);stroke-width:2;transition:fill .25s,stroke .25s}.tn text{fill:var(--ink);font:600 13px ui-monospace,Menlo,monospace}
.tn.hot circle{fill:var(--hot);stroke:#e5a400}.tn.hot text{fill:var(--hot-ink)}.tn .tl{font:700 11px system-ui,sans-serif;fill:var(--accent)}.tnone{color:var(--mute);font-size:13px}

.srow.stree{display:block;overflow-x:auto}.srow.stree .tsvg{margin:0}

.llist .cw,.llist .sc{position:relative;margin-right:26px}.llist .cell{border-radius:9px}
.llist .cw::after,.llist .sc::after{content:"\2192";position:absolute;right:-22px;top:50%;transform:translateY(-62%);color:var(--mute);font-size:17px;pointer-events:none}
.llist .cw.lst::after,.llist .sc.lst::after{content:"\2192 None";right:-52px;font-size:11px;font-style:italic;transform:translateY(-55%)}
.llist .cw.lst,.llist .sc.lst{margin-right:52px}